Iran unveiled a new “super” stealth fighter jet on Saturday, boasting advanced features and an original design — but according to critics it might be a hoax, or at least something much less impressive than what Iran has claimed. In the days since photos of the new aircraft were released, several problems have been identified by aviation experts and other observers who doubt the jet’s authenticity.

As the BBC notes, Iran doesn’t have a lot of options when it comes to obtaining new aircraft; the country has been restricted from buying new planes, hardware, or spare parts due to sanctions over its nuclear program.

Aviation blogger David Cenciotti has offered the most in-depth critique, concluding that the aircraft would never fly in its current form “unless extensive modifications are made.” Cenciotti writes that the jet has “a really peculiar design” that’s too small to house any radar equipment, a cockpit too small for a pilot, and air intakes too small to feed an engine.

“Overall, the plane seems to lack the characteristic rivets, bolts all aircraft, including stealthy ones, feature,” Cenciotti writes. “Images released so far show it has a plastic made aircraft.” Other missing details, like an engine exhaust nozzle, “would possibly melt the entire structure of the jet,” he says.